Due to increasing environmental concerns, alternatives to non-renewable and polluting fossil fuels have been investigated. Solar energy has received increasing attention as an alternative renewable, non-polluting energy source, and photovoltaic installations on commercial and residential roofs are becoming increasingly popular. The majority of existing installations to date consist of non-integrated systems. These systems generally consist of an array of photovoltaic or solar thermal modules attached on top of an existing roof covering.
“Add-on” structures can be installed on any type of roofing as “stand alone” solar systems. However, such systems typically require separate support structures that are bolted together to form an array of larger solar panels. Further, “add-on” solar panels are heavy and are more costly to manufacture, install and maintain. For example, the assembly of the arrays is typically done on-site or in the field rather than in a factory. Mounting arrays onto the roof may also require structural upgrades to the building.
Building Integrated Photovoltaics “BIPV” differ in that they act as roof covering and photovoltaic solution in one. BIPV solutions are required to interface with current roof coverings such as tiles, slates and metal roofing. This is because the whole surface of a roof is rarely used for power generation. The term “building-Integrated” is commonly used in the solar panel industry to differentiate this type of installation from that of a non-integrated system. This term implies that the photovoltaic or thermal solar panels constitute structural elements of a roof.
This invention is concerned particularly with integrated systems of the BIPV or solar thermal type, that are applicable to new roofs and can also be adapted to existing roofs.
Commonly used materials for photovoltaic panels include glass (as a support and protection for potentially delicate wafers) and extruded aluminum frames which are cut and assembled around the glass in much the same way as a picture frame. These assemblies are then attached to the roof by means of brackets. Some BIPV solutions on the market require a specific roof covering to be used, which diminishes the choice for a customer. Some other products on the market try to address this gap, however the choice of roof covering is often limited, and the installation can often be very time consuming in order to guarantee water-tightness of the installation. Other problems are that it is complicated to integrate some systems in standard sloped roofs; there are complications for installation and de-installation; and size limitations may lead to increased installation costs because installing many small panels is more labor intensive. Similar considerations apply to the installation of thermal solar panels.
US patent publication 2006/0196128 describes a mounting for solar panels that are inclined in asymmetric frames where a wedge-like bottom of one frame fits under a thick end of another frame, the frames being connected side-by-side by protruding interlocking fixings. The frame is a small unit designed to be moulded from recycled plastic.
US patent publication 2006/0042680 describes a BIPV structure with a plastic frame around a PV laminate, mounted on a polymer substrate for fitting on a rafter. This requires a complicated sealing arrangement.
WO 2008/052816 describes an integrated modular photovoltaic element designed to match with classic tiles, the element comprising a lower hollow structural part of plastic material and an upper convex element of light-transparent material. This structure is relatively complex.
U.S. Pat. No. 7,012,188 describes a BIPV framing system for solar panels made up of interconnected frame elements joined with a capping element over facing edges. This design requires a supplementary polymeric sealing strip.